The construction of a conventional portable lavatory will be described herein below, with reference to FIGS. 1 and 2 that show a portable lavatory according to an embodiment of the present invention.
As shown in FIGS. 1 and 2, a portable lavatory typically comprises a lavatory facility unit 11 and a tank unit 12. The lavatory facility unit 11, which is typically equipped therein with a toilet, a washbowl, etc., constitutes an upper part of the portable lavatory. The tank unit 12, which constitutes a lower part of the portable lavatory, feeds water from a fresh water tank thereof to the lavatory facility unit 11, and stores in a foul water tank thereof the foul water drained from the lavatory facility unit 11. To allow the portable lavatory to be used for a lengthy period after every filling of water in the fresh water tank and every emptying of the foul water tank the portable lavatory may be designed to contain a large quantity of water in the fresh water tank and a large quantity of foul water in the foul water tank. However, the above-mentioned design of the portable lavatory must be accompanied by an increase in each of the water containing capacity the tank unit 12 and the size of the portable lavatory.
To transport portable lavatories of various sizes to desired places, a variety of trucks may be used. To move a large-sized portable lavatory from a place to another place, a large-sized truck or a truck tractor with a trailer may be used. However in the case of a medium- or small-sized portable lavatory, a medium-sized truck may be used to transport the portable lavatory to a desired place.
In conventional portable lavatories, the length and width of the lavatory facility unit are equal to those of the tank unit, so that the sidewalls of both the lavatory facility unit and the tank unit are integrally continued to form a flat outer surface of the sidewalls. Thus, a conventional small-sized portable lavatory may be safely transported to a desired place while the portable lavatory is stably loaded into an open freight box 2 of a truck 1, which is defined on a bed 3 of the truck 1 by one front panel, two side gates 4 and one tailgate 5 that respectively stand along the front, side and rear edges of the bed 3. However, the small-sized portable lavatory provides only a small-capacity tank unit 12 having both a small fresh water tank and a small foul water tank, so that a manager of the small-sized portable lavatory installed on a place must frequently refill the fresh water tank with water and frequently empty the foul water tank.
A conventional large-sized portable lavatory may not be loaded in the freight box 2 of the truck 1 of which the two side gates 4 and the one tailgate 5 stand along the edges of the bed 3. Therefore, the two side gates 4 and the one tailgate 5 of the freight box 2 must be opened prior to loading the large-sized portable lavatory onto the bed 3. In the above state, the opened side gates 4 and the opened tailgate 5 may not be fastened to any part of the truck 1, so that the opened side gates 4 and the opened tailgate 5 may clatter during a transportation of the portable lavatory. Furthermore, the width of the large-sized portable lavatory exceeds the width of the bed 3, so that both side parts of the portable lavatory protrude outward to substantial lengths from both sides of the bed 3. In the above state, it is not easy to firmly or stably tie the portable lavatory to the truck 1 using a rope, due to the protruding side parts of the portable lavatory, so that the large-sized portable lavatory loaded on the bed 3 is not stable, thus sometimes unexpectedly moving on the bed 3 to be dropped from the bed 3 onto a road or the ground around the road during the transportation of the portable lavatory. Furthermore, the protruding side parts of the large-sized portable lavatory loaded on the bed 3 may collide on materials or persons placed or walking along roadsides or may strike against another vehicle passing by the truck 1 while the truck 1 runs along the road to transport the portable lavatory to a desired place. Thus, the protruding side parts of the large-sized portable lavatory loaded on the bed 3 may cause safety hazards during the transportation of the portable lavatory.
Furthermore, the tank unit 12, which constitutes the lower part of the conventional portable lavatory, is divided into the fresh water tank and the foul water tank by a fixed partition wall that is fixedly installed in the tank unit 12. Thus, the fresh water tank and the foul water tank respectively have fixed capacities. Thus, when the fresh water tank is in an almost full state by refilling the fresh water tank, the foul water tank is in an almost empty state. On the contrary, when the foul water tank is in an almost full state, the fresh water tank is in an almost empty state. Thus, the conventional portable lavatory is problematic in that the capacity of tank unit 12 of the portable lavatory is not effectively used.